尿素硝酸铵调节碳氮比促进小麦秸秆堆肥腐熟

【目的】高温堆肥可以加快秸秆腐解并浓缩其养分含量,是秸秆综合利用的有效措施之一。通常采用畜禽粪便来调节秸秆堆肥的C/N比,但由于重金属和抗生素问题限制了其在高价值经济作物上的应用。为此选择绿色无污染的尿素硝酸铵溶液(UAN)作为氮素调理剂开展堆肥试验,为生产高品质秸秆有机肥提供科学依据。【方法】设置4个处理,按照UAN添加量由多到少分别将堆肥C/N调节为15、20、25和30,进行50d堆肥,监测堆肥过程中温度、pH、EC、有机碳、铵态氮、硝态氮、纤维素组成、种子发芽率指数等指标的动态变化,并综合判定堆肥腐熟效果。【结果】C/N25和C/N30的处理最高温度分别达到63.4℃和65.9℃,50℃以上高温持续时间分别为7d和8d,而C/N15、C/N20处理高温持续仅1~2d,未达到无害化处理要求。堆肥初始pH值随着UAN添加量的增大而升高,范围在6.79~7.94,堆肥后pH值范围在7.63~7.89,各处理间没有明显差异。堆肥后各处理有机碳含量下降了8.29%~13.5%,且C/N25、C/N30的处理有机碳降解率显著高于C/N15和C/N20的处理。全氮含量较堆肥初增加53.3%~83.7%。秸秆中有机物组成表现为纤维素>半纤维素>木质素,堆肥后半纤维素、纤维素和木质素含量分别较堆肥初下降了30.5%~50.9%、42.%~55.8%和15.3%~29.4%。堆肥过程中由氨气挥发造成的氮素损失率随着C/N比升高而降低,分别为34.9%、29.0%、22.1%和7.37%;堆肥过程中无机氮占总氮的比例逐渐降低,由初始的52.4%~75.8%下降到结束时的25.4%~63.1%,而对应有机氮的比例则较堆肥初提高了52.4%~66.0%,表明小麦秸秆堆肥中氮素的稳定性增强。经过50d的堆肥处理,C/N25和C/N30的处理种子发芽率指数均达到彻底腐熟(GI≥80%),C/N20的处理达到基本腐熟(GI≥50%),而C/N15的处理未腐熟。【结论】采用尿素硝酸铵溶液作为氮素调理剂可有效降低小麦秸秆堆肥C/N比,促进小麦秸秆腐解,以C/N30处理腐熟效果最好。     

城市污泥与调理剂混合堆肥过程中有机质组分的变化

【目的】研究城市污泥堆肥过程中各项有机质组分及碳、 氮在堆肥过程中的形成与转化,以期改善堆肥的生物有效性,促进其土地利用。【方法】在工厂规模化下,以城市污泥、 蘑菇渣锯末以及返混料按照6∶3∶1的质量比混合形成堆肥物料,辅以强制通风措施和翻抛,进行为期18 d的高温堆肥试验。堆肥期间定期采样,测定指标包括温度、 C/N值、 pH、 含水率、 有机质降解率、 水溶性组分、 半纤维素、 纤维素和木质素,研究堆肥期间不同阶段堆肥物料中有机质组分的动态变化。【结果】堆体温度随着发酵时间的延长呈现先升高后降低的趋势,最高温度达到71.3℃; 含水率由60.7%降低到51.4%,pH呈现先升高后降低的趋势,总体处于6.0~7.5之间; 总有机碳含量持续下降,氮素含量表现为高温期持续下降随后呈上升的趋势; 初始阶段,堆肥物料中四种成分含量分布为: 水溶性组分纤维素半纤维素木质素,至堆肥结束变化为: 纤维素水溶性组分木质素半纤维素,经过堆肥之后水溶性组分及半纤维素含量分别由39.5%和20.1%下降为27.9%和14.4%,纤维素含量由初始的21.8%上升至29.5%,木质素含量相对稳定不变。物料经过堆肥化处理后达到腐熟标准,水溶性组分和半纤维素含量分别降低了38.6%和38.8%,纤维素和木质素含量在高温期分别降解了11.7%和18.5%; 物料总量降低了9.8%。水溶性组分的主要降解阶段为高温期,期间降解部分占总降解量的65.5%; 半纤维素的主要降解阶段为稳定期,稳定期降解部分占总降解量的69.1%,且有继续降解的趋势; 纤维素和木质素仅在高温期有少量降解; 氮素则表现为高温期铵态氮的损失及稳定期硝态氮的积累。【结论】堆肥化处理在实现污泥减量化基础上,污泥中有机质得到了稳定化,有利于城市污泥的土地利用。     

Evolution of Organic Matter Within Sixty Days of Composting of Lignocellulosic Food Industry Waste in Malaysia

Empty fruit bunches (EFB), coffee grounds (CG), and palm oil mill sludge (POMS) were composted in the laboratory for 60 days in order to study the composting process of lignocellulosic food industry wastes. In the first part of the experiment, EFB, CG, and POMS were composted alone (composting of single lignocellulosic material), and in the second part, EFB was composted with CG (1EFB:1CG ratio) and POMS (1EFB:1POMS ratio). The effects of different turning frequencies on the physical and chemical properties of composting were observed and its relation with the degradation process was highlighted. Results showed that oil and grease were first degraded, followed by recalcitrant compounds like alpha-cellulose, hemicellulose, and lignin. Cellulose and hemicellulose were degraded mainly during the 60 days of composting, and the progressive reduction of the cellulose/lignin ratio proved that the main evolution of these wastes took place. It was observed that 3, 6, and 9 days of turning frequency did not affect the physicochemical properties of the compost. Composting EFB alone failed to achieve the required quality of maturity compost within 60 days, while CG and POMS recorded low in biological activity. Better results were shown in composting of EFB mixed with coffee grounds and POMS, the C/N ratio dropped to less than 20 by the 8th week of the composting period. Composting of mixed lignocellulosic materials showed larger changes compared to composting of single lignocellulosic material, reaching a C/N ratio below 20 within 8 weeks.     

Degradation of DEHP,PAHs and LAS in Source Separated MSW and Sewage Sludge During Composting

The efficiency of composting to remove the pollutants DEHP, PAHs and LAS from organic waste products was investigated. Source separated MSW and sewage sludge, respectively, were composted at temperatures ranging from 35 to 70°C using a laboratory-scale reactor composting system. At regular intervals, compost samples were taken from the reactors for chemical analysis. DEHP disappeared rapidly during composting of MSW; 96 to 99% of the initial content was degraded within 25 days of composting regardless of process temperature. In sewage sludge, the highest degradation of 91% was reached at a composting temperature of 65°C. LAS degradation in sewage sludge was fastest at 55°C, but at both process temperatures tested 99% of the initial content had been removed within 25 days. Degradation of PAHs was less complete. However, in all composting experiments, with MSW as well as sewage sludge, the final PAH concentration was less than in the starting material. Further experiments suggested that less than 0.1% of the pollutants had evaporated. Thus, composting proved to be a promising technique to promote degradation of organic pollutants — especially DEHP and LAS — in MSW and sewage sludge.     

立式筒仓反应器堆肥技术工艺优化研究

反应器堆肥技术作为一种新型快速堆肥方式逐渐被人们所认可，该技术包括反应器堆肥处理和陈化两个阶段，但反应器堆肥时长和通气方式等工艺参数对堆肥全过程的影响尚不清楚。因此，本研究立足生产中的实际问题，利用12 m³立式堆肥反应器，开展了反应器堆肥工艺优化调控试验，以鸡粪和锯末为原料，分别研究了连续供气和间歇供气（风机开3 min，关7 min）两种供气方式下，反应器处理周期对堆肥有机质降解率、产品含水率、氮素损失和运行成本的影响。研究结果表明：反应器堆肥10 d比2 d的处理物料有机质降解率分别增加60.7%（间歇）和66.2%（连续），产品含水率分别降低41.2%（间歇）和40.7%（连续）。反应器堆肥阶段是物料降解的主要阶段，利用反应器堆肥的时长越长，堆肥产品生产时间越短；但运行成本的增加也对反应器堆肥时长造成了限制，同时增加反应器堆肥时长也会增加堆肥物料的氮素损失，其中连续供气反应器堆肥10 d比2 d氮素损失增加17.5%。连续供气方式可提高堆肥效率，较间歇供气处理堆肥周期平均缩短32.1%，产品全氮含量平均提高7.4%，虽然反应器堆肥阶段每日能耗较间歇供气高20.2%，但堆肥周期的缩短使全程连续供气平均运行成本降低16.5%。其中，连续供气下反应器中处理6 d、8 d和10 d，堆肥产品理化性质无显著差异。综合考虑堆肥效率、产品和经济，本试验建议选择“连续供气方式+反应器内堆肥8 d”处理，既可提高反应器堆肥处理效率，在实际生产中又具有较高的经济效益潜力。     

添加木炭改善猪粪稻壳好氧堆肥工艺及质量

为促进农业废弃物的资源化利用,试验以猪粪和稻壳为原料,用化学分析和仪器分析相结合的方法,研究了添加不同质量分数（0、2.5%、5.0%、7.5% 和10.0%）的木炭对60 d猪粪好氧堆肥过程的影响。结果表明：在堆肥有机质的降解过程中,含-OH、-CH3和-CH2基团的化合物的质量分数逐渐减少,含-C=O、C-O-C、-COO基团和含芳香环类物质的质量分数逐渐增加。添加木炭能促使堆肥物料的降解,随着木炭添加量的增加,在60 d的堆肥过程中,各处理有机碳的质量分数分别降低了12.23%、13.77%、14.88%、15.36%和15.86%,碳氮比分别下降了47.80%、54.98%、56.97%、60.03%和65.73%。与对照相比,添加木炭可延长堆肥高温期的停留时间3～ 5 d,增加堆肥物料的持水能力并降低堆肥产品的电导率;同时,添加木炭还能减少堆肥初期氨气的挥发,提高铵态氮的质量分数,促使堆肥后期硝态氮的转化。堆肥结束时,添加木炭可使硝态氮的质量分数提高55.86%～89.32%,总氮的质量分数提高20.55%～53.07%,雪里蕻种子发芽率提高17.6%～41.2%,萌发指数达1.02～1.44。研究表明,添加木炭能促进堆肥有机物料的降解,加快堆肥腐熟脱毒,增加堆肥产品总氮的质量分数,提高产品质量。木炭作为一种潜在的猪粪堆肥添加剂,在促进农业废弃物资源化利用方面具有广阔的应用前景。     

Transformations of carbon and nitrogen during composting of animal manure and shredded paper

Composts produced from animal manures and shredded paper were characterized in terms of their carbon (C) and nitrogen (N) forms and C mineralization. Total, water-soluble, acid-hydrolyzable and non-hydrolyzable C and N contents were determined on composts sampled on days 0, 11, 18, 26, 33, 40 and 59 after composting was initiated. Water-soluble and acid-hydrolyzable C and N decreased during composting, whereas non-hydrolyzable C remained relatively constant, and non-hydrolyzable N greatly increased during composting. The water-soluble forms of N were characterized by a decrease of ammomium (NH₄ ⁺-N) at the beginning of composting, followed by an increase of nitrate (NO₃ ^–-N) towards the end of composting. The mineralization of C in composted materials was generally higher at the beginning than at the end of composting, whereas no differences were observed for mineralization of C in non-hydrolyzable materials. The addition of N inhibited C mineralization in composts except in samples collected on days 40 and 59, while C mineralization was strongly stimulated by adding N to the non-hydrolyzable materials. The data suggest that the N forms in the non-hydrolyzable materials were chemically similar and not readily available to microbes, indicating that the C/N ratios often used to assess the biodegradability of organic matter and to develop compost formulations should be based on biologically available N and C and not on total N and C. Received: 12 May 1997     

碳氮比对鸡粪堆肥腐熟度和臭气排放的影响

为确定鸡粪堆肥最优碳氮比（C/N比）,该研究以新鲜鸡粪为堆肥原料,添加玉米秸秆调节初始C/N比为14、18和22进行好氧堆肥,研究不同C/N比对鸡粪堆肥腐熟度和臭气排放（NH3和H2S）的影响。结果表明：C/N比为14的处理堆肥产品未腐熟,C/N比为18和22的处理均达到腐熟。C/N比为18的处理NH3累积排放量和总氮（TN）损失率最高;C/N比为18～22时,C/N比越高,NH3累积排放量和TN损失率越低。C/N比为14的处理H2S累积排放量和总硫（TS）损失率最高;C/N比为18和22的两个处理,H2S累积排放量显著降低,且无显著差异。此外,C/N比为18处理的微生物群落多样性在整个堆肥过程中显著高于C/N比为14和22处理。堆肥的理化指标、臭气排放与微生物群落之间的相关性分析表明,高温、高pH和缺氧环境会增加Firmicutes丰度,进而促进NH3和H2S的排放,相反地,低温、低pH和氧气充足的环境更有利于Actinobacteria增殖,有利于减少NH3和H2S的排放。综合考虑堆肥产品腐熟度和臭气减排效果,建议低C/N比鸡粪堆肥的初始C/N比为18～22。当秸秆资源不足时,建议初始C/N比为18;秸秆资源充足时,建议初始C/N比为22。     

接种木质纤维素分解复合菌系对堆肥发酵进程的影响

以具有高效木质纤维素分解能力的复合菌系作为接菌剂,接种到以牛粪、鸡粪和麦秸为材料的堆肥化过程中,测定了各发酵参数和物质成分的变化.利用变性梯度凝胶电泳(DGGE)和末端限制性片断多态性(T-RFLP)分析方法,研究了堆肥发酵过程中微生物群落的动态.结果表明,接菌对堆肥化过程中温度、水分和pH值的影响不大.经63 d发酵之后,接菌处理的半纤维素、纤维素和木质素的减重率比不接菌处理分别高4.3%、3.0%和3.4%.接菌处理的各个发酵阶段C/N比也明显低于不接菌处理.DGGE和T-RFLP的结果显示,接菌后堆肥发酵初期复合系中的 Ureibacillus thermosphaericu、Pseudoxanthomonas taiwanensis、Tepidiphilus margaritifer、Rhizobiaceae str.M100、C thermobutyricum 和Bacillus thermoamylovorans 菌株大量定殖于堆肥体系中,DGGE图谱中可见接种处理堆肥体系中的条带数少于不接菌处理,而同一水平线的条带亮度明显高于不接菌处理.DGGE和T-RFLP的结果都表明接菌处理的微生物多样性少于不接菌处理.可见接种微生物在堆肥体系中占据优势,抑制了部分杂菌生长,促进了发酵进程.     

C/N对蓝藻好氧堆肥腐熟及无害化进程的影响

为探索和优化脱水蓝藻藻泥好氧堆肥无害化处理工艺参数,利用堆肥反应器,研究了C/N分别为5（T1）、15（T2）和25（T3）的处理对蓝藻藻泥腐熟进程及微囊藻毒素（MC）降解速率的影响。结果表明,堆肥过程中各处理间的pH、总碳量及其形态、总氮量及其形态、总磷含量、总钾含量、种子发芽指数差异显著。与蓝藻自然堆置相比,添加辅料增加堆体C/N可提高蓝藻的腐熟速度。堆肥35d后,T2和T3处理的堆肥成品均已满足有机肥行业标准,种子发芽指数均高于80%;但MC-LR和MC-RR仍有较大的降解潜力,从无害化的角度考虑,蓝藻高温堆肥时间不应少于50d。C/N过高增加了氮素的损失,如何进一步降低氮素的损失,提高堆肥过程中MC的降解将是今后蓝藻堆肥研究的重点。     

不同C N比堆肥碳素物质变化规律研究

针对堆肥化过程中常伴有少量CH4等温室气体排放造成环境污染等问题,采用密闭堆肥化装置,进行了不同碳氮比和通气条件下,堆肥过程中的气体释放规律、影响因子及其对堆肥理化性质的影响研究。结果表明,C/N=25、30堆肥处理的有机物降解率高于低碳氮比处理;全氮含量随着有机物的降解而浓缩,随着堆肥的进行而不断提高,到堆肥结束时,C/N=15、20、25和30处理的全氮含量分别为23.5、24、27.8 g.kg-1和28.4 g.kg-1;堆肥过程中,C/N=15、20、25和30的堆肥处理CH4累积排放为0.67、0.95、2.25g.kg-1和1.80 g.kg-1,损失比例占初始碳物质的0.39%、0.5%、1.24%和0.92%,并且CH4气体的排放主要集中在高温前期,高温期越长,排放的温室气体越多。高温期适当增大通气量,对于控制堆肥温度和减少温室气体生成有双重作用。     

Hydrothermal Treatment of Date Palm Lignocellulose Residue for Organic Fertilizer Conversion: Effect on Cell Wall and Aerobic Degradation Rate

Date palm (Phoenix roebelenii) woodchips, a residue of palm tree plantations, was subjected to hydrothermal treatment (HTT) at mild reaction conditions (160°C < T < 220°C, 0.6 MPa < P < 2.4 MPa) for 30 min, and the effect of treatments on the cell wall (CW) solubilization and subsequent aerobic degradation rate (as CO production) was tested under controlled composting conditions during 63 days of incubation (38°C). The HTT at 160 and 180°C reaction temperatures notably solubilized hemicellulose, decreasing the fraction of this CW polymer from 34.1% in the untreated material, to 9.5 and 4.6% in the respective residues. However, treatment at 200 and 220°C reaction temperatures rapidly liquefied the lignin, which apparently went into solution with hemicellulose and appeared to stabilize a portion of this polysaccharides against hydrolysis. Consequently, the fraction of hemicellulose in 200 and 220°C – treated residues gradually increased; the respective values were 5.8 and 9.4%. The treatment temperature of 180°C was the most effective HTT temperature for subsequent aerobic degradation by solubilizing the largest portion of hemicellulose within the CW, which had two consequences: 1) it supplied additional readily bioavailable form of carbon, which in turn promoted rapid microbial activities in the early stage of decomposition; and 2) it created pores and cavities within the CW, which permitted rapid bacterial penetration and CW degradation. As a consequence, biodegradation of the residue treated under this reaction temperature proceeded rapidly and stability was reached within 21 days, compared to 63 days of continued degradation for the untreated CW. The enhanced biodegradability was also partially linked to the effect of 180°C treatment temperature on solubilization of amorphous cellulose and partial hydrolysis of lignin. Based on the results, the HTT system can successfully be used as a pretreatment step to accelerate the aerobic digestion rate of date palm residues for the production of organic fertilizers.     

The Effect of Different C/N Ratios on the Composting of Pig Manure and Edible Fungus Residue with Rice Bran

The aim of this study was to determine the effects of initial C/N ratio (16.3, 19.1, 24.1, and 29.6) on decomposition rate and nitrogen loss during the composting of pig manure and edible fungus residue with rice bran. The results showed that all composting piles reached a temperature greater than 55°C for at least 7 days (which meets the requirements for destroying pathogens), and the maturity times of composts with low initial C/N ratios were shorter than in composts with high initial C/N ratios. The nitrogen loss in the composting pile with initial C/N of 16.3 was significantly higher than the other treatments. Furthermore, the statistics analysis showed that the initial C/N ratios of the composts, which varied from 16.3 to 29.6, had a significant negative linear correlation with the loss of total organic matter (R = ?0.9661) and loss of total nitrogen (R = ?0.9365). Therefore, for treating more agricultural wastes and achieving high-quality final product as well as the reduction of nitrogen losses, this study recommends that initial C/N ratios ranging from 20 to 25 are suitable for composting pig manure and edible fungus residue.

Highlight:

Various agricultural wastes can be successfully composted with initial C/N ratios 16:1–30:1.

Nitrogen loss had a significant linear negative correlation with the initial C/N ratio.

Compost with a low C/N ratio was beneficial to dispose of more pig manure since reducing the addition of carbon materials.     

Hemicelluloses of ragi (finger millet, Eleusine coracana, Indaf-15): isolation and purification of an alkali-extractable arabinoxylan from native and malted hemicellulose B

Hemicelluloses (A and B) were isolated from an Indo-African hybrid variety of finger millet (ragi, Eleusine coracana) by extracting the starch-free residue with 10% sodium hydroxide under a continuous stream of nitrogen, and changes in their sugar composition during malting for 96 h were studied. Hemicellulose B, obtained in higher yield from both native (N) and malted (M) flours, was found to be completely soluble in water, richer in uronic acid, and more viscogenic than hemicelullose A. Fractional precipitation of hemicellulose B by ammonium sulfate resulted in four precipitable fractions (F-60, F-70, F-80, and F-100) and a nonprecipitable (NP) fraction varying in their yield and arabinose, xylose, galactose, and glucose contents. A progressive increase in the pentose-to-hexose ratio (P:H) from 0.42:1.0 in F-60 to 1.94:1.0 in NP was observed in native hemicellulose B fractions; however, in malted hemicellulose B the P:H ratio increased from 0.43:1.0 in F-60 to 1.56:1.0 in F-80 and then decreased to 1.13:1.0 in NP. The major fraction, F-70 (N, 44.5%; M, 38.5%), was separated into eight subfractions on DEAE-cellulose by successive elution with water, ammonium carbonate (AC) (0.1, 0.2, and 0.3 M AC), and sodium hydroxide (0.1 and 0.2 M) differing in their yield and neutral sugar composition. The purity of the major glucuronoarabinoxylan fraction (0.1 M AC eluted) was ascertained by Sepharose CL-4B, HPSEC, cellulose acetate, and capillary electrophoresis methods. A significant decrease in the molecular mass of arabinoxylan from 1200 to 1120 kDa upon malting for 96 h is an indication of cell wall degradation by the inducible cell wall degrading enzymes.     

Changes in Physical,Chemical, and Microbiological Properties During the Two-Stage Composting of Green Waste due to the Addition of β-cyclodextrin

This research determined whether addition of β-cyclodextrin (β-CD; 0, 0.15, or 0.25%) improved the two-stage composting of green waste (GW). The following parameters were measured during composting or in the final product: moisture content; volume; biochemical and chemical oxygen demand; humic substances; C/N_solid and C/N_soluble; microbial numbers (culturable bacteria, actinomycetes, and fungi); enzyme activities (pectinase and xylanase); microbial biomass carbon and nitrogen; degradation of organic components; contents of phosphorus (available and total), potassium, sodium, calcium, and magnesium; and toxicity to germinating seeds. The two-stage composting of GW was optimal with the addition of 0.15% β-CD. A mature and stable compost was obtained in only 28?days with the optimized two-stage composting rather than in the 90–270?days typically required for traditional composting.     

The Effects of Goat Manure,Sewage Sludge And Effective Microorganisms on the Composting of Pine Bark

This study investigated the cocomposting of pine bark with goat manure or sewage sludge, with or without inoculated effective microorganisms (EM). Composting was done for 90 days and parameters monitored over this period included temperature, pH, electrical conductivity (EC), C/N ratio, inorganic N, as well as tannin content. Changes in temperature, pH and EC during composting were consistent with those generally observed with other composting systems. The parameters were influenced by the feedstock materials used but were not affected by inoculation with effective microorganisms. The highest temperature measured from pine bark-goat manure composts was 60°C but much lower maximum temperatures of 40°C and 30°C were observed for pine bark sewage sludge and pine bark alone composts, respectively. The C/N ratios of the composts decreased with composting time. Ammonium levels decreased while nitrate levels increased with composting time. Tannin levels generally decreased with composting time but the extent of decrease depended on the contents of the composting mixtures. The trends observed showed that temperature, pH, EC, C/N ratio, tannin levels, and inorganic NH₄-N and NO₃-N were reliable parameters for monitoring the co-composting of pine bark with goat manure or sewage sludge. The pine bark-goat manure compost had more desirable nutritional properties than the pine bark and pine bark-sewage sludge composts. It had high CEC, near neutral pH, low C/N ratio, and high amounts of inorganic N and bases (K, Ca, and Mg) while pine bark compost had the least amounts of nutrients, was acidic, and had high C/N ratio and low CEC. The final tannin content of the pine bark-goat manure compost was below the 20 g/kg upper threshold level for horticultural potting media, implying that its use as a growing medium would not cause toxicity to plants.     

Biodegradation of sunflower hulls with different nitrogen sources under mesophilic and thermophilic incubations

The decomposition of sunflower hulls and mixtures of sunflower hulls and other crop residues was examined under mesophilic (25°C) and thermophilic (50°C) temperatures during a 45-day incubation. Four treatments were set up: sunflower hull, sunflower hull+5% alfalfa, sunflower hull+5% vetch, sunflower hull+0.1% urea, to asses the efficiency of composting. Changes in total organic C (TOC), oxidizable C, N, pH, electrical conductivity (EC), and different fibre fractions—cellulose, hemicellulose and lignin—were determined. TOC decreased by 13–21% at 25°C and 25–41% at 50°C and the largest loss of C was for hulls amended with vetch residues and urea. Loss of oxidizable C was not affected by either the temperature or the treatments. The largest loss of cellulose occurred at 50°C in all the treatments. The hemicellulose content of the sunflower hulls alone and in the treatment with urea was significantly different with respect to the other treatments, whereas lignin content showed either a small increase (1.6% in sunflower hulls amended with alfalfa at 50°C and 1.8% in sunflower hulls with urea at 25°C) or a decrease of between 2.5% and 19% in the other treatments. The C/N ratio never fell below 50:1 and the highest decrease was for the thermophilic incubation. Increases in EC and pH values accounted for 3 and 1.5 units, respectively, and occurred after a 45-day incubation for mesophilic and thermophilic conditions. In general the incubation at 50°C facilitated the decomposition of sunflower hulls with high C/N ratios and little N addition.     

采用EEM-FRI方法研究黑曲霉对牛粪堆肥腐熟及纤维素降解影响

为了优化堆肥工艺,提高堆肥产品质量,研究黑曲霉对牛粪堆肥腐熟度和纤维素降解的影响.该研究以牛粪为原料,小麦秸秆为辅料,以不添加黑曲霉为对照,分别添加1％、2％和3％的黑曲霉进行好氧堆肥,研究了黑曲霉不同添加量对腐熟度指标、养分含量、腐殖质组成以及纤维素组分的影响,并采用激发发射荧光光谱结合荧光区域积分(Excitati...     

Composting By-Products from a Bleached Kraft Pulping Process: Effect of Type and Amount Of Nitrogen Amendments

Over 70% of solid wastes (by-products) generated in the manufacture of paper pulp are presently disposed of in landfills. Most of these by-products are compostable and reusable in horticulture, landscaping and agriculture. This work addresses the questions of nitrogen amendments required for composting a mix of four bleached kraft pulp mill by-products — namely, primary sludge, bark, grit and ash. Two nitrogen amendments, ammonium nitrate and chicken litter were compared to determine which provided a more rapid mass reduction and stabilization. Different amounts of ammonium nitrate addition were evaluated to determine if decreasing the C:N ratio of the initial mix (from 130.9 to 28.3) resulted in more rapid composting. A blend of sludge, grit, bark and ash in dry weight percentages of 56, 25, 6 and 13% respectively, stabilized (measured using oxygen respirometry) in a period of 28 days. Although in the initial stages of composting there were differences resulting from the effect of the two types of nitrogen amendments, at the 28th day no significant difference was observed. It was also found that decreasing the C:N ratio did not accelerate the composting process. A composting mix with a C:N ratio of 130.9 had similar mass reduction compared to others with C:N of 95.3, 79.5 and 28.3. Lower C:N ratios were in fact less preferable because of high soluble salt content and greater amendment requirements.     

汽爆麦草的两相法生物气化

蒸汽爆破作为一种新型的预处理方法被初次运用于麦草的两相气化系统,以碳酸氢铵作为补充氮源调节碳氮比,并在相同条件下以未汽爆麦草作对照试验。以汽爆麦草为原料时,水解反应器的pH值低于加入未汽爆麦草的pH值,并且在25 d后慢慢升至7;以两种麦草为原料时,甲烷反应器的pH都稳定在7左右,此时最适合甲烷生成。汽爆麦草的总固形物和挥发性固形物含量分别降低了57.5% 和62.1%,下降率差不多是未汽爆麦草的2倍;纤维素和半纤维素的降解率也有了显著的提高,分别为63.0% 和67.4%;木质素的降解率变化不大,都在5％左右。汽爆麦草的总产气量高于非汽爆麦草,并且一直保持较高的增长率,而非汽爆麦草的增长率一直较低;两种麦草产生的生物气中的甲烷含量大致相同,在水解反应器中后期为50％左右,在甲烷反应器中为70％左右。以上结果表明,汽爆可以促进麦草的降解,提高生物气的产量,是一种行之有效的预处理技术。